They've had a graphical design team for years. This is nothing new. Let that team do what that team is good at. Adding graphical elements to an already existing framework (the data used to authenticate FaceID) is trivial. Everyone harping on about "Durr durr durr why all the new emojis durr durr" kinda miss the point that these things already exist and are being skinned. Animoji was probably put together initially to demonstrate/test FaceID. Someone in management likely saw it and thought it would be popular with the general/non technical public, which it is, and figured that the graphics team could polish it into a neat feature. Emoji are part of the Unicode spec. In order to support Unicode, you have to support emoji. Someone has to design those emoji and, oh my goodness, there's a graphics team who can do exactly that.